Visa said today it is buying online payment platform PlaySpan for $190 million in cash, “plus additional consideration for performance milestones.”

Visa said the acquisition complements its further expansion into digital and mobile commerce.  The deal follows Visa’s purchase of another online payment company, CyberSource in July.

The acquisition is expected to be completed in Visa’s fiscal second quarter 2011 and is expected to slightly dilute the company’s earning per share in its fiscal year 2011 ending September 30, 2011.

Last year, global ecommerce sales reached an estimated $948 billion and they remain a significant growth opportunity for Visa. Approximately 45 percent of U.S. online spend takes place on Visa’s network today.